Fabrication of racetrack-type double-pancake coils using 2G tapes and online mechanical shock test

Abstract

Racetrack-type double-pancake (DP) coil was wound successfully with YBCO high-temperature superconducting tapes. The characteristics and impact resistance of the coils were investigated. The characteristics of the dependent DP coil did not change after applying different acceleration values in the X and Y directions. With the increasing value of acceleration (i.e., up to 30 g in X direction and 15 g in Y direction), the voltage of the racetrack coil remained unaffected. Based on the tests, three racetrack-type coils were wound and assembled in a certain sequence to form a magnet. The optimum temperature range for impregnating the magnet was confirmed by investigating the viscosity and shear stress of paraffin at different temperatures. After the assembly of the coils, the magnet was vacuum impregnated with liquid paraffin. Subsequently, the magnet was fixed in a Dewar that was filled with liquid nitrogen to cool the coils. The magnet was energized after cooling down. Then, the mechanical shock resistance of the coils in Dewar was tested dynamically. Results showed that the coil characteristics did not change after paraffin impregnation. The voltage and magnetic field were almost unaffected by the dynamic increase in the acceleration value to up to 30 g every 5 g interval in the X direction. Thus, these methods of construction and paraffin impregnation and fixtures can be used in the racetrack-type magnet.